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211.
Ganesh Narayanan Yavuz Caydamli Halil Tekinalp Ishita Matai Ramiz Boy Ching-Chang Chung Jialong Shen Bhupender S. Gupta Alan E. Tonelli 《Journal of polymer science. Part A, Polymer chemistry》2018,56(22):1529-1537
Three pseudorotaxanes (PpR) comprised of poly (ε-caprolactone) (PCL) and α-cyclodextrin (α-CD) with varying stoichiometric ratios were synthesized and characterized. Wide-angle X-ray diffraction (WAXD) and thermogravimetric (TGA) analyses provided conclusive evidence for complexation between the guest PCL and host α-CD. The as-synthesized and characterized PpRs were used at 10 and 20% concentrations as nucleants to promote the bulk PCL crystallization in composite films. Both WAXD and TGA provided evidence for intact PpR structures in the composite films. Isothermal differential scanning calorimetric (I-DSC) analyses, performed at various crystallization temperatures demonstrated significant differences in the crystallization patterns among the composite films. In addition, I-DSC analyses showed higher Avrami constant values (n) in the PpR-nucleated composite PCL films (n ~ 3), indicating 3-dimensional crystal growth. In the case of neat PCL films, however, lower n values indicated crystal growth in 1-dimensions or 2-dimensions. Moreover, atomic force microscopic analyses showed large crests and pits in PpR-nucleated PCL composites, with irregular morphologies leading to higher surface roughness. To the contrary, the crests and pits were much smaller in the neat PCL films, resulting in lower surface roughness values. Finally, mechanical testing revealed higher tensile strength for PpR-nucleated PCL composites films, demonstrating larger load bearing capabilities. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018 , 56, 1529–1537 相似文献
212.
The anti-selective aldol reaction of chiral alcohol-substituted γ-benzyloxy vinylogous urethanes is described. The use of (1S,2R,4R)-1-(hydroxydiphenylmethyl)-7,7-dimethylbicyclo[2,2,1]-heptan-2-ol as a chiral auxiliary in the aldol reaction of a vinylogous urethane enolate was found to provide anti-products in good yields with moderate to excellent enantioselectivities. The major anti-vinylogous urethane lactones were transformed into 3-benzyloxyl-4-hydroxylalkan-2-ones in good yields. 相似文献
213.
Kinetics and Mechanism of the Reaction of a Ruthenium(VI) Nitrido Complex with HSO3− and SO32− in Aqueous Solution 下载免费PDF全文
Dr. Qian Wang Hong Yan Zhao Dr. Wai‐Lun Man Dr. William W. Y. Lam Dr. Kai‐Chung Lau Prof. Tai‐Chu Lau 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(31):10754-10758
The kinetics and mechanism of the reaction of SIV (SO32?+HSO3?) with a ruthenium(VI) nitrido complex, [(L)RuVI(N)(OH2)]+ (RuVIN, L=N,N′‐bis(salicylidene)‐o‐cyclohexyldiamine dianion), in aqueous acidic solutions are reported. The kinetic results are consistent with parallel pathways involving oxidation of HSO3? and SO32? by RuVIN. A deuterium isotope effect of 4.7 is observed in the HSO3? pathway. Based on experimental results and DFT calculations the proposed mechanism involves concerted N?S bond formation (partial N‐atom transfer) between RuVIN and HSO3? and H+ transfer from HSO3? to a H2O molecule. 相似文献
214.
215.
Sang Hyun Park Younghwan Jin Kyunghan Ahn In Chung Chung-Yul Yoo 《Journal of Electronic Materials》2017,46(2):848-855
The structural and electrical characteristics of Ag/Ni bilayer metallization on polycrystalline thermoelectric SnSe were investigated. Two difficulties with thermoelectric SnSe metallization were identified for Ag and Ni single layers: Sn diffusion into the Ag metallization layer and unexpected cracks in the Ni metallization layer. The proposed Ag/Ni bilayer was prepared by hot-pressing, demonstrating successful metallization on the SnSe surface without interfacial cracks or elemental penetration into the metallization layer. Structural analysis revealed that the Ni layer reacts with SnSe, forming several crystalline phases during metallization that are beneficial for reducing contact resistance. Detailed investigation of the Ni/SnSe interface layer confirms columnar Ni-Sn intermetallic phases [(Ni3Sn and Ni3Sn2) and Ni5.63SnSe2] that suppress Sn diffusion into the Ag layer. Electrical specific-contact resistivity (5.32 × 10?4 Ω cm2) of the Ag/Ni bilayer requires further modification for development of high-efficiency polycrystalline SnSe thermoelectric modules. 相似文献
216.
Residual determination and risk assessment of buprofezin in plum (Prunus domestica) grown in open‐field conditions following the application of three different formulations 下载免费PDF全文
Md. Humayun Kabir A.M. Abd El‐Aty Sung‐Woo Kim Han Sol Lee Md. Musfiqur Rahman Young‐Jun Lee Hyung Suk Chung Truong Lieu Jeong‐Heui Choi Ho‐Chul Shin Geon‐Jae Im Su Myeong Hong Jae‐Han Shim 《Biomedical chromatography : BMC》2016,30(11):1721-1727
This study was conducted to characterize the residual level and perform a risk assessment on buprofezin formulated as an emulsifiable concentrate, wettable powder, and suspension concentrate over various treatment schedules in plum (Prunus domestica). The samples were extracted with an AOAC quick, easy, cheap, effective, rugged, and safe, ‘QuEChERS’, method after major modifications. As intrinsic interferences were observed in blank plum samples following dispersive‐solid phase extraction (consisting of primary secondary amine and C18 sorbents), amino cartridges were used for solid‐phase extraction. Analysis was carried out using liquid chromatography with diode array detection and confirmed by liquid chromatography–tandem mass spectrometry. The method showed excellent linearity with determination coefficient (R2 = 1) and satisfactory recoveries (at two spiking levels, 0.5 and 2.5 mg/kg) between 90.98 and 94.74% with relative standard deviation (RSD) ≤8%. The limit of quantification (0.05 mg/kg) was considerably lower than the maximum residue limit (2 mg/kg) set by the Codex Alimentarius. Absolute residue levels for emulsifiable concentrates were highest, perhaps owing to the dilution rate and adjuvant. Notably, all formulation residues were lower than the maximum residue limit, and safety data proved that the fruits are safe for consumers. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
217.
Media as Educator,Media as Disruptor: Conceptualizing the Role of Social Context in Media Effects 下载免费PDF全文
We document how social contexts serve to refract media effects. We theorized the relationship between media use and individual‐level knowledge (and attitude) would be stronger when community‐level knowledge (and attitude) was low than when it was high. Data come from a national survey (N = 12,608 women and 1,237 men) conducted in Nepal. Knowledge and stigma toward people living with HIV were the 2 dependent variables. Hypotheses were tested 12 times: across the use of 3 media (newspaper, radio, television) × 2 study outcomes (knowledge and attitudes) × 2 genders. Predicted interactions were supported in 9 of the 12 tests. Findings point to the need to take into account the role of community factors in theorizing about media effects. 相似文献
218.
219.
Poly[3,3-bis(chloromethyl)] oxetane in vacuo, after λ-irradiation at 77°K and room temperature, showed ESR spectra consisting of a triplet (hfs of 22.0G) and a doublet (hfs of 17.8G), respectively. The triplet ESR spectrum is attributed to the -CH2-C(CH2Cl)-CH2 -O- radical and the doublet ESR spectrum is attributed to the -CH2-C(CH2Cl)2-CH-O- radical. The G values for formation of radicals are estimated to be 0.3 and 0.5 at 298 and 77°K, respectively. 相似文献
220.
Wei Ye Qiang Shi Shing‐Chung Wong Jianwen Hou Hengchong Shi Jinghua Yin 《Macromolecular bioscience》2013,13(6):676-681
Platelets play a fundamental role in thrombus formation and in the pathogenesis of arterial thrombosis. Patterning surfaces for controlled platelet adhesion paves the way for adhesion and activation mechanisms in platelets and detection of platelet functional defects. Here, a new and simple method based on controlled polymerization of 2‐methacryloyloxyethyl phosphorylcholine (MPC) on the surface of styrene‐block‐(ethylene‐co‐butylene)‐block‐styrene (SEBS) is shown. The competition between polymerization and degradation enables platelet adhesion on SEBS to be switched on and off. The adhesive sites of the platelets can be down to single cell level, and the dysfunctional platelets can be quantitatively detected.